With regard to the above node by Orange Julius (that the Great Wall isn't particularly discernible from space), there is additional information as to the visibility of the Great Wall from space.

An American astronaut, Gene Cernan, told the Straits Times (a reputable daily newspaper; THE newspaper in Singapore) that he saw the Great Wall from outer space with his own eyes. He was giving an interview in Singapore, when he attended the Asian Aerospace 2004, a biannual airshow.

Eugene A. Cernan served aboard Gemini IX (June 3-6, 1966), Apollo 10 (May 18-26, 1969) and Apollo 17 (December 6-19, 1972). During his first space mission, he became the second American to walk in space. He was also slated in backup positions for Gemini 12, Apollo 7 and Apollo 14. Having spent a precise 556 hours and 15 minutes in space, out of which more than 73 hours was spent on the Moon, he is uniquely qualified to speak on this subject.

His exact quote was: 'At Earth orbit of 160km to 320km high, the Great Wall of China is indeed visible to the naked eye.' He also confirmed that it was not observable from the moon; however, only continents and oceans are perceivable across that distance.

The skill involved with sighting the Great Wall, apparently, lies in knowing where to look and eyeballing it hard enough. From this we can deduce that the Great Wall is not easily noticeable from space. Depending on your knowledge of geography, your perseverance, how good your eyesight is and the weather conditions, you might (or might not) be able to see the Great Wall.

Therefore, when other space cadets such as the newbie Chinese astronaut Colonel Yang Liwei said that the thin, undulating structure could not be viewed from space, he probably lacked one or more of the factors listed above. (I stand corrected: I found out that he orbited at about 350 kilometers from Earth; perhaps he was too far away to be able to see the Wall.)

Although the notion that the Great Wall was easily discernible in space was blasted as an urban legend, NASA's position that it could not be perceived due to its narrow width and its earth-like colouration also needs revision.

Incidentally, the fact that the Great Wall is perceptible from outer space is about to be struck from Chinese textbooks in mainland China because of Col. Yang's report.


The Straits Times Interactive - http://straitstimes.asia1.com.sg/
You can view the Straits Times article "You can see the Great Wall from space" online at http://straitstimes.asia1.com.sg/news/story/0,4386,240173,00.html? from 14th March 2004 to 17th March 2004, only, after which it will be archived and inaccessible except for a fee.

Biographical Data of Eugene A. Cernan - http://www.jsc.nasa.gov/Bios/htmlbios/cernan-ea.html

Orbit details of Chinese manned space mission: "Report: Manned space mission to orbit earth 14 times" - http://www1.chinadaily.com.cn/en/doc/2003-10/09/content_270451.htm

An Associated Press report: "China to Correct Great-Wall-In-Space Myth" - http://www.newsday.com/news/nationworld/world/wire/sns-ap-china-great-wall-myth,0,6755225.story?coll=sns-ap-world-headlines